The present invention relates to a sequence program search method of searching for a net in the sequence program of a programmable controller (PC), and more specifically, to a sequence program search method by which a required net can be easily found when the sequence program is debugged, or the like.
1. Field of the Invention
Programs in a ladder form are widely used in the sequence programming of a programmable controller (PC), and these ladder programs are expressed in a relay logic form, where one logic line is referred to as a net.
The ladder program is created by a program creation unit, and after having been debugged, is stored in the programmable controller (PC) for use. When the ladder program is debugged, a search must be made for a required net.
For example, if a coil signal is not actuated when needed, a search must be made for a contact signal used for actuating the coil signal. Usually, this search is carried out by using the symbol or net number, or the like, of the contact signal.
Nevertheless, since respective contact signals are not always arranged sequentially, such a search takes a long time, and thus a problem arises when the sequence program is debugged. Further, when the size of the programmable controller (PC) is increased, and accordingly, the capacity of the sequence program is increased, such a search cannot be easily carried out.
In particular, in debugging a search for the same signals must be often made to confirm whether the logic of the sequence program is correct.